Goals: Ulysses primary science target was our Sun, but the solar orbiter's unique orbit and long lifespan produced three unexpected encounters with comet tails and a chance for bonus science.

Accomplishments: The spacecraft's May 1996 encounter with comet Hyakutake revealed comet tails are far longer than expected. The tail extended half a billion kilometers (more than 300 million miles) - more than three times the distance from the Earth to the Sun. The discovery marked the longest comet tail - streams of ions, gas and dust extending away from the Sun - recorded at the time.